SharpMap v2.0 is nearing Beta quality, where the API is settling down and you will be able to use the parts which are completed without worrying about large API changes (which have been occuring in the Alpha code).

The selection and highlighting mechanisms are nearly complete - the final task now is to complete the rather complex state-machine which emerges between different views (Map View, Layer View and Attribute View) when selecting features. It is progressing, however,
and I really need to have it done soon, myself. Last week would have been nice, for example.

As for WPF, that is mostly not implemented. However, doing so should not take long since it amounts to creating a renderer and a view, and I'll likely also need to do this relatively soon for a project. I fully expect WPF to be quite a bit faster and more featureful,
however.

I'm fairly certain that the Beta 1 binary bits which will be released will have selection and highlighting for GDI, so pick up a
feed from the releases and get notified when it happens.